This product is a high purity, non-natural D-threo ceramide that is ideal as a standard and for biological studies. D-erythro ceramide is the natural ceramide isomer and is involved in many biological processes including induction of cell maturation, cell cycle arrest, terminal cell differentiation, cell senescence, and cell death.1 Both the natural D-erythro and the non-natural L-erythro and the D- and L-threo ceramides display similar effectiveness in inducing apoptotic damage in cells.2 The protein phosphatases PP1 and PP2A, which are involved in regulating apoptosis and cell growth, are activated by D-erythro ceramide but inhibited by D-threo ceramide and the other two non-natural ceramide stereoisomers.3 Both D-erythro and Dthreo C2 ceramides have been found to be potent inducers of IL-6 production, while neither of the L- isomers of ceramide were effective.4 D- and L-erythro ceramide and D- and L-threo ceramide are also comparably effective inhibitors of protein kinase C.5